This information comes right from the NIH's (National Institute of Health) website.

An increasing number of doctors believe that some of the most severe cases of migraines may actually be caused by an imbalance of key minerals such as magnesium and calcium. "Not all headaches are produced by this imbalance, but we now know that 50 to 60 percent of migraines are magnesium-linked. And that's probably why no prescription therapy on the market successfully treats headaches across the board. They're simply not treating the cause," says Dr. Altura. "Of the 17 people we've treated with magnesium, 13 have had complete improvement," says Herbert C. Mansmann, Jr., M.D., professor of pediatrics and associate professor of medicine at Jefferson Medical College of Thomas Jefferson University in Philadelphia.

The magnesium-migraine link still is not commonly accepted by headache experts. In fact, Dr. Altura says that one of his magnesium studies was rejected by a prominent medical journal at the suggestion of a top headache researcher. (Shortly thereafter, the study was published by another journal.) But the weight of evidence for magnesium's use in the treatment of migraines is building. "There's no question that the literature strongly supports it," says Dr. Mansmann. "The so-called headache experts don't believe the data because they don't know anything about the development of magnesium deficiencies within cells."

To understand why magnesium might do the trick, it helps to take a look at how migraines happen. Migraines are thought to be caused by vascular changes, or changes in the blood vessels, that reduce blood or oxygen flow in the scalp and brain. What causes these vascular changes? Things such as muscle contractions during times of stress and biochemicals called catecholamines and serotonin, which are circulating in the blood. Too much serotonin can cause blood flow to slow; too little can cause blood to move through too rapidly, explains Dr. Altura.

While mainstream researchers have long known that changes in serotonin and catecholamine levels cause migraine pain, stopping these changes has been a hit-or-miss proposition, says Dr. Altura. An aspirin, for example, temporarily inhibits the effects of serotonin but does nothing to prevent a migraine from coming back, he says. Dr. Altura says he's the first to prove that loss of magnesium from the brain is behind the problem. Without enough magnesium, serotonin flows unchecked, constricting blood vessels and releasing other pain-producing chemicals such as substance P and prostaglandins, he says. Normal magnesium levels not only prevent the release of these pain-producing substances but also stop their effects, says Dr. Altura.

It's very likely that magnesium deficiency is a widespread cause of migraines, maintains Dr. Mansmann. What's more, several different things, from the caffeine in just two cups of coffee a day to the chemicals in most asthma medications, remove some magnesium from your system. "We know that intake is low for a lot of people. We know that a lot of medications, such as diuretics (water pills) and a variety of cardiovascular medications, can increase magnesium losses. We know that people with diabetes who have high blood sugar lose a lot more magnesium in the urine and, as a result, run the risk of magnesium deficiency," says Karen Kubena, Ph.D., associate professor of nutrition at Texas A&M University in College Station. Even stress, a frequent cause of migraines, can remove magnesium from your system, says Dr. Mansmann.

According to his records, Dr. Altura says that about 50 to 60 percent of his migraine patients have low magnesium levels. But once they begin treatment, he says, they often experience immediate relief. "We can say that 85 to 90 percent of these patients are successfully treated, and that's pretty miraculous," says Dr. Altura. So can getting more than your share of magnesium every day prevent migraines? Dr. Altura says it's still unclear. "I'd like to be able to answer that question. I can't at this point, but my guess is that it would," he says. "The active form of magnesium is ionized magnesium. When a substance is chemically bound, it's sort of neutralized, if you want to use a Star Trek term. When it's ionized, it is available to do what it is supposed to do, which in this case is possibly prevent constriction of blood vessels in your brain and scalp," explains Dr. Kubena.